Etching apparatus of glass substrate

ABSTRACT

The present invention discloses an etching apparatus comprising an etching bath having an etchant; an etchant recycling part in the etching bath; a DI and undiluted etchant supply part for supplying a DI water and a undiluted etchant; an etchant mixing part for mixing the DI water and the undiluted etchant; and an etchant heating part for heating the mixed etchant.

This application claims the benefit of Korean Patent Application No.2000-83103 filed on Dec. 27, 2000, which is hereby incorporated byreference as if fully set forth herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an etching apparatus of a glasssubstrate, and more particularly, to an etching apparatus of a glasssubstrate using a heating unit.

2. Discussion of the Related Art

Recently, research of flat panel displays such as liquid crystal display(LCD), plasma panel display (PDP), electroluminescent display (ELD),vacuum fluorescent display (VFD), etc., is being performed and thesedisplays are being used in various apparatus.

Among these displays, LCDs are most widely used in that they have goodpicture quality and low power consumption characteristics. They arebeing used as the display in portable televisions and notebookcomputers.

Portable televisions or notebook computers are obtaining the popularitydue to their lightness in weight. A main component of technologydevelopment is to decrease their weight. To this end, there are specificefforts to decrease the weight of the LCD itself.

Various ways for decreasing the weight of the LCD have been tried.However, LCD structure and current technology limit the decrease ofweight and size to the main elements of the LCD.

In the meanwhile, glass substrate, which is one of the most basicelements of the LCD, still has margin to decrease the weight of the LCDaccording to developments in processing technologies. Since the glasssubstrate occupies most of the total weight of the LCD, research fordecreasing the weight of the glass substrate is being performed for thepurpose of decreasing the weight of the LCD.

In order to decrease the weight of the glass substrate, its thicknessshould be decreased preferentially. However, if the thickness decreasesbelow a specific value, the glass substrate is broken during itsprocessing or cracks are generated. Therefore, there is a limitation indecreasing the thickness of the glass substrate.

As a way for decreasing the thickness of the glass substrate, after anLCD is fabricated using a glass substrate having the specific thicknessand more, the glass substrate is etched by dipping the glass substratein an etching bath in which an etchant is contained.

This method, however, has disadvantages in that the glass substrate isnonuniformly etched due to the incompleteness of the glass substrateitself, or foreign particles generated during the etch process are againattached to the etched surface of the glass substrate and thus thesurface of the glass substrate becomes irregular.

Hereinafter, a conventional etching apparatus is described withreference to the accompanying drawings.

FIG. 1 is a block diagram of a conventional etching apparatus of glasssubstrates.

First, a method for fabricating an LCD using a glass substrate isdescribed.

A pair of large-sized glass substrates each having plural pixel regionsare prepared. An LCD panel is fabricated using the pair of glasssubstrates by attaching the glass substrates with a space between theglass substrates. The LCD panel is cut to have a selected size. Liquidcrystal is injected into the space between the glass substrates.

Specifically, in the LCD panel, on one glass substrate, generally called“TFT substrate”, gate lines and data lines normal to the gate lines areformed to thereby define pixel regions. A pixel electrode is formed onthe defined unit pixel region. On the other glass substrate, generallycalled “color filter substrate”, color filter of red, green, blue (R, G,B) and a common electrode are arranged. The TFT substrate and the colorfilter substrate are aligned with a space for the liquid crystal betweenthem and then they are attached each other. The attached substrates arecut and then the liquid crystal is injected into the space.

In the aforementioned LCD panel fabrication process, the attachedsubstrates are etched to decrease the weight of the substrates prior tocutting the attached substrates.

Referring to FIG. 1, the conventional etching apparatus includes: anetching bath 1 for etching a glass substrate using an etchant to aselected thickness; a cleaning bath 6 for cleaning the etched substrateusing deionized (DI) water; a drying bath 7 for drying the cleanedsubstrate; an etchant recycling part 2 for reproducing the etchant usedin the etching bath 1; a DI supply part 3 for supplying DI water ordistilled water; an undiluted etchant supply part 4 for supplying aundiluted etchant; and an etchant for mixing the DI and the undilutedetchant supplied from the DI supply part 3 and the undiluted etchantsupply part 4 respectively with the recycled etchant supplied from theetchant recycling part 2 and supplying the mixed etchant to the etchingbath 1.

FIG. 2 shows a detailed constitution of the etching bath 1 described inFIG. 1.

Referring to FIG. 2, the etching bath 1 includes: a container 1 acontaining the etchant; a bubble plate 1 c established at a lowerportion of the container 1 a, for uniformly distributing a bubble usinga gas supplied from an outside source; a gas supply tube 1 b forsupplying nitrogen (N₂) or oxygen (O₂) to the bubble plate 1 c; and acontainer cover 1 d for covering the upper portion of the container.

Here, generating the bubbles using nitrogen or oxygen gas is touniformly etch the surface of the glass substrate by removing a reactantremaining on the surface of the etched glass substrate when the glasssubstrate is etched by an exothermic reaction with the etchant used.

The etchant mixing part 5 is connected to the etching bath 1 to supplythe mixed etchant to the etching bath 1. The DI supply part 3 and theundiluted etchant supply part 4 are respectively connected to theetchant mixing part 5 to supply the DI water and the undiluted etchantto the etchant mixing part 5.

The etchant mixing part 5 has to mix the DI water and the undilutedetchant with the refined etchant in a constant concentration. To do so,a concentration measuring part 5 a is provided in the etchant mixingpart 5. The concentration measuring part 5 a measures the concentrationof the etchant mixed in the etchant mixing part 5. When theconcentration of a finally mixed etchant in the etchant mixing part 5arrives at a reference concentration, the concentration measuring part 5a informs a control part (not shown) of such a fact. By the control ofthe control part, the supply from the DI supply part 3 and the undilutedetchant supply part 4 is stopped.

The glass substrate is etched in the etch container 1 a of the etchingbath 1 by an exothermic reaction between the glass substrate and thefinally mixed etchant supplied from the etchant mixing part 5.

The aforementioned conventional etching apparatus, however, has adrawback as follows.

As described above, since the glass substrate is etched in the etchcontainer 1 a of the etching bath 1 by an exothermic reaction betweenthe glass substrate and the finally mixed etchant, and the etchantmixing part 5 supplies the finally mixed etchant to the etching bath 1at a room temperature, a long etch time is required.

SUMMARY OF THE INVENTION

It is, therefore, an object of the present invention to provide anetching apparatus of a glass substrate capable of shortening the etchtime by heating an etchant for etching the glass substrate to a certaintemperature and supplying the heated etchant to an etching bath.

Additional features and advantages of the invention will be set forth inthe description which follows, and in part will be apparent from thedescription, or may be learned by practice of the invention. Theobjectives and other advantages of the invention will be realized andattained by the structure particularly pointed out in the writtendescription and claims hereof as well as the appended drawings.

To achieve the above object, there is provided an etching apparatuscomprising: an etching bath having an etchant; an etchant recycling partin the etching bath; a DI and undiluted etchant supply part forsupplying a deionized (DI) water and an undiluted etchant; an etchantmixing for part mixing the DI water and the undiluted etchant; and anetchant heating part for heating the mixed etchant.

BRIEF DESCRIPTION OF THE DRAWINGS

It is understood that both the foregoing general description and thefollowing detailed description are exemplary and explanatory and areintended to provide further explanation of the invention as claimed.

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention andtogether with the description serve to explain the principles of theinvention.

In the drawings:

FIG. 1 is a block diagram showing an etching apparatus of glasssubstrates in accordance with the conventional art;

FIG. 2 is a block diagram showing the etching bath of the etchingapparatus of FIG. 1;

FIG. 3 is a block diagram showing an etching apparatus of glasssubstrates in accordance with an embodiment of the present invention;and

FIG. 4 is a detailed block diagram of FIG. 3.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Reference will now be made in detail to the preferred embodiment of thepresent invention, example of which is illustrated in the accompanyingdrawings.

In the following description, same drawing reference numerals are usedfor the same elements even in different drawings. The matters defined inthe description such as a detailed construction and elements of acircuit are nothing but the ones provided to assist in a comprehensiveunderstanding of the invention. Thus, it is apparent that the presentinvention can be carried out without those defined matters. Also,well-known functions or constructions are not described in detail sincethey would obscure the invention in unnecessary detail.

FIG. 3 is a block diagram of an etching apparatus in accordance with onepreferred embodiment of the present invention.

Referring to FIG. 3, an etching apparatus includes: an etching bathhaving an etchant and for etching a glass substrate for an LCD; acleaning bath 16 for cleaning the etched substrate using a deionized(DI) water, etc.; a drying bath 17 for drying the cleaned substrate; anetchant recycling part 12 for removing a foreign particle contained inthe etchant used in the etching bath 11 and storing the foreignparticle-removed etchant; a DI supply part 13 for supplying DI water ordistilled water; an undiluted etchant supply part 14 for supplying anundiluted etchant; an etchant mixing part 15 for mixing the DI and theundiluted etchant supplied from the DI supply part 13 and the undilutedetchant supply part 14, respectively, with the recycled etchant suppliedfrom the etchant recycling part 12 to a certain concentration; and anetchant heating part 18 for heating the mixed etchant to a certaintemperature.

Here, the etchant includes an HF solution.

FIG. 4 is a detailed block diagram of FIG. 3.

Referring to FIG. 4, the etching bath includes; an etchant container 11a, containing the etchant; a bubble plate 11 c established at a lowerportion of the container 11 a, for generating bubbles using a gassupplied from outside; a gas supply tube 11 b connected to the bubbleplate 11 c in a form of at least one tube, for supplying nitrogen (N₂)or oxygen (O₂) gas; a temperature measuring unit 11 e established withinthe container 11 a; and a container cover 11 d for covering thecontainer 11 a.

Here, the temperature measuring unit 11 e is used in controlling theetch time. In other words, the etchant as used is to remove siliconoxide (SiO₂) contained in the glass substrate. Thus, a reaction betweenthe glass substrate and the HF solution is expressed as the followingchemical equation Eq. 1.SiO₂+HF→SiF₄+2H₂O+E  Eq. 1

where, numeral “E” is the heat generated when the glass substrate isetched.

Thus, since heat is generated upon etching the glass substrate, it ispossible to know the degree of etching performed by measuring thegenerated heat regardless of the concentration of the etchant used andthe etch time. Accordingly, a temperature of the reaction heat iscomputed depending on the thickness and number of a desired substrateand the etch process is stopped as the real temperature of the etchantarrives at the computed value, so that a substrate having a uniformthickness is obtained.

The etchant recycling part 12 includes a filter 12 a for removing aforeign particle remaining in the etching bath 11 after etching thesubstrate in the etching bath 11 and a storage tank 12 b for storing theetchant refined through the filter 12 a.

A concentration measuring unit 15 a is installed within the etchantmixing part 15 to measure the concentration of the etchant mixed in theetchant mixing part 15. Selectively, a PCW tube is installed at aselected portion within the etchant mixing part 15 to constantlymaintain the temperature of the mixed etchant.

The concentration measuring unit 15 a helps to constantly maintain theconcentration of the etchant such as HF solution. This is because theconcentration of the etchant, as well as a pressure of bubbles of thenitrogen or oxygen gas, affects the etch time. In other words, when theconcentration of the etchant is low, the etch time is lengthened, whilewhen the concentration of the etchant is high, the surface of the glasssubstrate is non-uniformly etched due to an abrupt exothermic andchemical reaction, and thus a spot is generated on the surface of theglass substrate.

The filter 12 a is connected to a rear end of the storage tank 12 b andis preferably connected to the rear end and the front end of the storagetank 12 b at least one. The filter 12 a removes sludge deposited withinthe storage tank 12 b.

To transfer the etchant, tubes are connected between the etching bath 11and the etchant heating part 18, between the etchant heating part 18 andthe etchant mixing part 15 and between the etchant mixing part 15 andthe etchant recycling part 12. At least one pump is installed betweenthe tubes.

Next, an operation mechanism of the etching apparatus having theaforementioned constitution is described.

A glass substrate for an LCD is dipped in the etch container 11 a of theetching bath 11, and the pump (not shown) between the etching bath 11and the etchant heating part 18 is operated. An etchant is heated by theetchant heating part 18 and is transferred to the etch container 11 a ofthe etching bath 11 through a tube. An exothermic reaction between theheated etchant and the glass substrate is generated in the etchcontainer 11 a and thus the glass substrate is etched. At this time,oxygen or nitrogen gas is injected into the bubble plate 11 c of theetching bath 11 from the gas supply tube 11 b, and thus bubbles aregenerated in the etchant contained in the etch container 11 a. Thegenerated bubbles remove foreign particles adhered to the surface of theglass substrate.

After that, the used etchant is transferred from the etch container 11 ainto the etchant recycling part 12 through a tube connected betweenthem. The etchant is refined by passing through the filter 12 a and thenis stored in the storage tank 12 b. Afterwards, the refined etchant isagain transferred to the etchant mixing part 15. Then, the etchantmixing part 15 mixes the refined etchant with DI water or distilledwater supplied from the DI supply part 13 and the undiluted etchantsupplied from the undiluted etchant supply part 14.

At this time, when the concentration of the mixed etchant in the etchantmixing part 15 arrives at a reference concentration, the etchant mixingpart 15 stops the supply from the DI supply part 13 and the undilutedetchant supply part 14 using the concentration measuring unit 15 ainstalled therein.

The etchant mixed in a constant concentration within the etchant mixingpart 15 is introduced into the etchant heating part 18 through a tubeconnected between them and then is heated at the etchant heating part 18in a temperature higher than the room temperature. The heated etchant isagain introduced into the etch container 11 a of the etching bath 111 bythe pump pressure.

Then, an exothermic reaction occurs between the supplied etchant and theglass substrate, and thereby the glass substrate dipped is etched. Thetemperature measuring unit 11 e of the etching bath continuouslymeasures a temperature variation of the etchant contained in the etchcontainer 11 a generated by the exothermic reaction. As a result of themeasurement, when the measured temperature does not arrive at thereference temperature, the aforementioned steps are repeatedlyperformed, while when the measured temperature arrives at a referencetemperature, the etch process is automatically stopped.

As described previously, the etching apparatus of the present inventionhas the following advantages.

First, the etchant is heated and thus a fast exothermic reaction betweenthe etchant and a workpiece such as glass substrate occurs, so that theetching rate is enhanced.

Second, the enhanced etching rate allows the amount of the undilutedetchant which is used for constantly maintaining the concentration ofthe etchant to be decreased, so that production costs are substantiallylowered.

In other words, since the exothermic reaction between the etchant andthe glass substrate at a temperature higher than the room temperatureshortens the reaction time greatly over that at the room temperature,the etching apparatus of the present invention shortens the reactiontime, thereby improving the performance of the apparatus.

It will be apparent to those skilled in the art that variousmodifications and variation can be made in the present invention withoutdeparting from the spirit or scope of the invention. Thus, it isintended that the present invention cover the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

1-19. (canceled)
 20. A method of etching a material, comprising:providing an etchant in an etching bath; providing a material to beetched in the etching bath to etch the material; monitoring temperatureof the etchant in the etching bath after the material is provided in theetching bath; and stopping etching of the material in the etching bathwhen the temperature of the etchant is a predetermined value.
 21. Themethod of claim 20, further comprising: maintaining a constantconcentration of the etchant in the etching bath.
 22. The method ofclaim 20, wherein the material to be etched is glass.
 23. The method ofclaim 20, wherein the etchant is HF.
 24. The method of claim 20, furthercomprising: heating the etchant in the etching bath.